The present invention relates to a novel family of compositions based on alkyl polyglycosides and fatty alcohols, which are useful especially for preparing stable, fluid emulsions.
The invention is especially applicable in the cosmetic field.
Alkyl glycosides or alkyl polyglycosides (APG) are well-known non-ionic surface-active compounds which can be used on their own, or in association with other surfactants, in a broad range of industrial applications and especially in the cosmetics sector.
Alkyl polyglycosides were first used as foaming agents and, in this application, those with an alkyl chain containing from 8 to 14 carbon atoms were found to be of particular value.
More recently, alkyl polyglycosides have been used as emulsifiers and, in this application, those with an alkyl chain containing from 16 to 18 carbon atoms have proved to be of particular value.
Patent application WO 92/06778, in the name of the Applicant, describes for the first time the use of mixtures of alkyl polyglycosides and fatty alcohols as self-emulsifying agents.
&lt;&lt;Self-emulsifying&gt;&gt; designates any agent or composition which is capable of forming a stable emulsion with an aqueous phase, practically without the provision of energy, for example by dispersion in the aqueous phase by slow, mechanical agitation.
More specifically, the mixtures described in this prior art document comprise:
60 to 90% by weight of at least one fatty alcohol having 12 to 22 carbon atoms, and preferably 16 to 18 carbon atoms; and PA1 10 to 40% by weight of an alkyl polyglycoside, the alkyl part of which is preferably identical to that of the fatty alcohol. PA1 5 to 60% by weight of a mixture of alkyl polyglycosides essentially consisting of: PA1 95 to 40% by weight of one or more alcohols of formula R'OH, in which R' is a linear or branched aliphatic radical having 12 to 22 carbon atoms, and preferably of a mixture consisting of alcohols the alkyl part of which is identical to the alkyl part R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 of the alkyl polyglycosides mentioned above. PA1 10 to 20% by weight of an alkyl polyglycoside of formula (I): EQU R.sub.1 O(G.sub.1).sub.X.sub..sub.1 (I) PA1 15 to 25% by weight of an alkyl polyglycoside of formula (II): EQU R.sub.2 O(G.sub.2).sub.X.sub..sub.2 (II) PA1 0 to 10% by weight of a mixture of alkyl polyglycosides of formulae (III) and (IV): PA1 50 to 70% by weight of a mixture of alkyl polyglycosides of formulae (V) and (VI): EQU R.sub.5 O(G.sub.5).sub.X.sub..sub.5 (V) EQU R.sub.6 O(G.sub.6).sub.X.sub..sub.6 (VI) PA1 10 to 40% by weight of a mixture of alkyl polyglycosides as defined above, PA1 90 to 60% by weight of one or more alcohols as defined above. PA1 19.9% by weight of a mixture of alkyl polyglycosides essentially consisting of: PA1 80.1% by weight of one or more alcohols of formula R'OH, in which R' is a linear or branched aliphatic radical having 12 to 22 carbon atoms, and preferably of a mixture consisting of alcohols the alkyl part of which is identical to the alkyl part R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 of the alkyl polyglycosides mentioned above. PA1 oils of plant origin, such as sweet-almond oil, coconut oil, castor oil, jojoba oil, olive oil, rapeseed oil, groundnut oil, sunflower oil, wheat germ oil, maize germ oil, soya oil, cotton oil, lucerne oil, poppy oil, marrow oil, evening primrose oil, millet oil, barley oil, rye oil, safflower oil, canelle nut tree oil, passion flower oil, hazelnut oil, palm oil, shea butter, apricot kernel oil, Alexandria laurel tree oil, sysymbrium oil, avocado oil, and calendula oil; PA1 modified plant oils such as the products known by the INCI names Apricot Kernel Oil PEG-6 esters and Olive Oil PEG-6 esters; PA1 oils of natural origin, such as perhydrosqualene and squalene; PA1 mineral oils such as paraffin oil ; and mineral oils originating especially from petroleum cuts, such as isoparaffins with boiling points of between 300 and 400.degree. C.; and PA1 synthetic oils, especially fatty acid esters such as butyl myristate, propyl myristate, cetyl myristate, isopropyl palmitate, butyl stearate, hexadecyl stearate, isopropyl stearate, octyl stearate, isocetyl stearate, dodecyl oleate, hexyl laurate and propylene glycol dicaprylate; ester derivatives of lanolic acid, such as isopropyl lanolate and isocetyl lanolate; triglycerides such as glycerol triheptanoate; alkyl benzoates; isoparaffins; polyalphaolefins; polyolefins; synthetic isoalkanes such as isohexadecane and isododecane; and silicone oils. Among the latter oils, there may be mentioned more particularly dimethylpolysiloxanes, methylphenylpolysiloxanes, silicones modified by amines, silicones modified by fatty acids, silicones modified by alcohols, silicones modified by alcohols and fatty acids, silicones modified by polyether groups, epoxy-modified silicones, silicones modified by fluorinated groups, cyclic silicones and silicones modified by alkyl groups.
The self-emulsifiable compositions described in the patent application cited above are marketed under the name Montanov.RTM. 68 and contain a mixture of alkyl polyglycosides whose fatty chains contain 16 and 18 carbon atoms, and a mixture of fatty alcohols with the same length of fatty chains.
Although such compositions are perfectly satisfactory, especially in terms of the stability of the emulsions obtainable therewith, these emulsions do not however enable fluid emulsions to be obtained easily.
Furthermore, International patent application WO 95/13863, in the name of the Applicant, also describes compositions based on alkyl polyglycosides and fatty alcohols, which are in the form of concentrates, which enable the preparation of fluid emulsions.
These compositions are essentially characterised by the fact that they comprise a mixture of at least two alkyl polyglycosides which differ in the nature of their alkyl part, at least one of these alkyl polyglycosides containing an alkyl chain having 16 to 22 carbon atoms, and preferably 16 to 18 carbon atoms and representing at least 25%, and preferably at least 50% by weight, of the mixture of alkyl polyglycosides.
Although the compositions described in this prior art document are satisfactory as regards the fluidity of the emulsions obtainable therewith, it has been observed that these emulsions are not entirely satisfactory from the point of view of their stability.
In practice, it is generally necessary to employ such compositions at a high use amount, or in association with a co-surfactant or with a stabiliser.